<template>
  <div>
    第三个组件 --- {{ count }}

    <div class="box">
      <div class="small"></div>
    </div>
  </div>
</template>

<script>
export default {
  data() {
    return {
      count: null,
    };
  },
  created() {
    this.$bus.on("send", (value) => {
      this.count = value;
    });
  },
};
</script>

<style lang="scss">
.box {
    width: 100px;
    height: 100px;
    background: red;
}
</style>